In order to reduce power consumption, mission managers have turned off a heater on part of NASA’s Voyager 1 spacecraft, dropping the temperature of its ultraviolet spectrometer instrument more than 41° Fahrenheit (23° Celsius). It is now operating at a temperature below –110° F (–79° C), the coldest temperature that the instrument has ever endured. This heater shut-off is a step in the careful management of the diminishing electrical power so that the Voyager spacecraft can continue to collect and transmit data through 2025.

At the moment, the spectrometer continues to collect and return data. It was originally designed to operate at temperatures as low as –31° F (–35° C), but it has continued to operate in ever chillier temperatures as heaters around it have been turned off over the past 17 years. It was not known if the spectrometer would continue working, but since 2005, it has been operating at –69° F (–54° C); so, engineers are encouraged that the instrument has continued to operate, even after the nearby heater was turned off in December. (The spectrometer is likely operating at a temperature somewhat lower than –110° F (–79° C), but the temperature detector does not go any lower.)

Scientists and mission managers will continue to monitor the spectrometer’s performance. It was very active during Voyager 1’s encounters with Jupiter and Saturn, and since then an international team led by scientists in France has been analyzing the spectrometer’s data.

This latest heater shut-off was actually part of the nearby infrared spectrometer, which itself has not been operational on Voyager 1 since 1998.